Answer:
400,000,000,200,000,000
Explanation:
First you need to start with
500,000,000 x 800,000,000
this is because multiplication always comes first even if its not at the start of the equation.
500,000,000 x 800,000,000= 400,000,000,000,000,000
Then add 200,000,000
An easy way to do this is line them up like this:
400,000,000,000,000,000
200,000,000
then put the 200,000,000 in where it lines up
400,000,000,200,000,000
And there's your answer